Lower End Rattle

[hudsonguy]

I'm in the process of rebuilding my '49 262 motor, as some of you know from another thread, and wanted to ask about something I discovered when I took it apart.

First of all, several times last summer (three as I recall), I experienced what someone described to me as a 'death rattle'. Not unlike preignition pinging, but lower in the engine, and more metallic than that. Two of these incidents were when I was going through the Sierra Nevada mountains after the Reno Nationals, when I was on the west coast, as some of you may recall. Eventually, the engine developed a faint knock you could hear easily when cold, and whenever under acceleration, even after it warmed up.

So I was quite curious what I would find in the engine when I tore it apart. Other than a little bearing scoring hear and there (and a small crack in the block, but that's another thread), the only other thing I found out of place or out of tolerance was the No. 2 Rod Cap. It was ever so slightly 'chewed' up underneath one of the nuts. This nut was actually torqued to about 70#, rather than the recommended 55, which all of the others were. My guess is that this rod bolt was overtightened at one time, and lost it's ability to stretch. I do know that rod bolts are designed to stretch, like an axial spring, in order to keep the nuts tight. I'm planning on replacing all of the rod bolts and nuts, which are readily available, and spot facing the rod cap.

Has anyone experienced this particular problem. Do you think this was the 'rattle' and/or 'knock' I was hearing in the engine? Am I all wet?

This is my first Hudson engine experience, so I'm curious what you Hudson veterans might think about this.

As always, thank for the help and advice.

Hudsonly,
Doug

[51hornetA]

What did the oil pump gear look like? was it worn to the point where a lot of the meat of the teeth is gone. When you look at the gear you will see the teeth look like they are very thin. When this happens the gear chatters and you get a bit of noise in the engine. You can also loose some teeth and these pieces chew up your bearings.

Also since I think you said your crack was in a valve seat that valve would not cool properly and you would get ping in that cylinder which would cause a knock sound.

[hudsonguy]

The oil pump gear was replaced, so it was basically new. I'd replaced the original the year before, as it was indeed worn out pretty well. But that was not the sound now, anyway.

Yes, the crack is across #6 intake valve seat. Basically, it lines up with the valve and bore 'centers', and is about .350" deep, as measured at the top of the bore. I hadn't thought about this valves 'cooling'

Thanks,
Doug

[maasfh]

Would suggest you check the crank for roundness on the rods and mains. I assume you will turn the crank anyway. May be good idea to have the big end resized after replacing rod bolts and nuts.

Randy